DRUGS ALTERING BONE METABOLISM Flashcards
what drugs can affect bone metabolism?
chronic corticosteroid administration of corticosteroids is a major risk factor for the development of osteoporosis by increasing the rate at which bone is broken down and reducing the body’s ability to reabsorb calcium, and thiazide diuretics decrease the renal excretion of calcium and are associated with a decrease in fractures and calcium oxalate renal stones.
how do bisphosphonates work, what is bioavailability of alendronate and what factors affect it, what is the dosing regimen and why is it different for etidronate and alendronate? What is major complication of alendronate treatment and and how can it be prevented, what type of fracture do bisphosphonates appear to increase?
BP’s work by inhibiting osteoclasts (cells involved in the breakdown and calcification of bone). This ultimately favours bone formation over bone resorption.
Oral absorption is very poor (<1%) due to the highly charged atoms due to multiple charged phosphonate groups leading to decreased absorption, however this is still sufficient for them to be dosed orally.
Bisphosphonates shouldnt be taken with hard water with many minerals because it could decrease absorption.
Bisphosphonates are corrosive, and can cause esophagitis if the patient lays down after taking the pill as it can reflux back into the esophagus.
Alendronate is more potent that etidronate and selectively inhibits osteoclasts, whereas etidronate is less potent, requires higher dosing and inhibits both osteoclasts and osteoblasts (osteoblasts favor bone formation), in order to prevent inhibition of osteoblasts, a greater dosing interval is required when taking etidronate at higher doses whereas alendronate can be given daily due to selective osteoclast inhibition.
Bisphosphonates are associated with greater femur fractures and osteonecrosis of the jaw, should be stopped after a few years of treatment which shouldnt have too big of an effect since the half life of bisphosphonates are measured in years.
